Introduction to plc (s7)­

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Introduction to plc (s7)­

  1. 1. SIEMENS SIMATIC S7 INTRODUCTION TOPROGRAMMABLE LOGIC CONTROL Revision 2
  2. 2. ASSESSMENT» Practical Test 1 – 20%» Practical Test 2 – 20%» Assignment – 20%» Final Exam – 30%» Key Qualification – 10%
  3. 3. MODULE OBJECTIVESUpon completion of this course, the participants will be able to:» explain the basic ideas on PLC such as PLC components’ signaling, I/O addressing and program execution;» apply PLC programming method such as LAD, FBD and STL using Siemens STEP 7 software;» define and explain Siemens STEP 7 PLC software such as RS, timers, counters, load and transfer commands, comparisons and arithmetic functions.
  4. 4. Handout section 1.0 Topic 1 Basic Principle of Control Technology
  5. 5. PLCPROGRAMMABLE LOGIC CONTROL (PLC):“ A digital electronic device that uses a programmable memory to store instructions and to implement specific functions such as logic, sequence, timing, counting and arithmetic to control machines and process. “
  6. 6. Definition of ControlWhat is CONTROL?“ CONTROL is the process in a system in which one or several input variables influence other variables “DIN 19226
  7. 7. A Simple View of a Control System INFORMATION C S SENSORS O Y P N S L T T A COMMANDS R E ACTUATORS N O M T L
  8. 8. Types of Control System CONTROL SYSTEM OPEN-LOOP CLOSED-LOOPCONTROL SYSTEM CONTROL SYSTEM
  9. 9. Open-loop Control SystemIn open-loop control systems, output variables areinfluenced by the input variables. L N
  10. 10. Closed-loop Control System It is characterized by continuous comparison of the desired value (or set point) with the actual value of the controlled variable.L Xi > Xs CXi - Required value XiXs - Actual value Xs Xi < Xs N
  11. 11. Handout section 1.1 PLC and Conventional Control System The essential difference between programmable control and traditional control technology may be summed up as follows: » The functions are no longer determined by the wiring, but rather by the program » Programming is simplified to enable symbols familiar to the control engineer to be used (contacts or logic graphic symbols)
  12. 12. Handout section 1.3 Hardwire and PLC Wiring Diagrams L 24 VDC S1 S1 S2 S2 K1 PLC K1 K1 N 0V Hardwire PLC
  13. 13. Comparison Hardwired control systems Programmable control system» The functions are determined » The functions are determined by the physical wiring. by a program stored in the memory.» Changing the function means » The control functions can be changing the wiring changed simply by changing the program.» Can be contact-making type » Consist of a control device, to (relays, contactors) or which all the sensors and electronic type (logic circuits) actuators are connected.
  14. 14. HISTORY OF PLC» During the late 1960s, General Motors (USA) was interested in the computer application to replace the hardwire systems.» Bedford Associates (Modicon) and Allen Bradley responded to General Motors.» The name given was “Programmable Controllers” or PC.» Programmable Logic Controller or PLC was a registered trademark of the Allen Bradley.» Later, PC was used for “Personal Computer” and to avoid confusion PLC for “Programmable Controller” and PC for a personal computer.
  15. 15. ADVANTAGES OF PLC COMPARED TO HARDWIRE» Implementing changes and correcting errors» Pilot run - trial / test run» Visual observation - online monitoring» Speed of operation» Reliability» Documentation
  16. 16. PLC Application Example CONVEYOR LINE WORKSTATION #1 WS #2 WS #3 FLOW OF MATERIAL
  17. 17. PLC Control System» Input devices ◊ Sensors M ◊ Switches etc. WS #1 WS #2 WS #3» Output devices ◊ Relays PLC 0032 ◊ Lamps etc» PLC
  18. 18. Handout section 2.0 ( Topic 2 ) Familiarization with STEP 7
  19. 19. Handout section 1.4 Basic Structure of a PLC POWER PG/ SUPPLY PC INPUT CENTRAL OUTPUT MODULES PROCESSING MODULES UNIT (CPU) MEMORY (EPROM/RAM)
  20. 20. PLC Inputs / Outputs (I/Os) USER PROGRAMInput OutputDevices (LOGIC) Devices PLC
  21. 21. Input Connections » Input card » Converter Input ◊ field voltage to 5V Devices acceptable by the CPU
  22. 22. Handout section 1.4.1 Input Interface / Module From field wiring Detection Bridge Signal Conditioning Logic Status Threshold Light Decision Opto-Isolation Logic To CPU / Memory
  23. 23. Output Connections» Output card» Converter ◊ 5V to field voltage Output to drive field devices Devices
  24. 24. Handout section 1.4.2 Output Interface / Module From CPU / Memory Logic Status Logic Light Opto-Isolation Switching Circuitry Protection Circuitry To field wiring
  25. 25. Input/output ConnectionsI ON PLC U MP T PU Logic U WS #1 WS #2 WS #3T TS S 0 0 32 PLC
  26. 26. Input / Output Modules» Digital input modules adapt digital signals e.g. from proximity sensors» Digital output modules convert the internal signal level of PLC into digital process signals e.g. relays» Analog input modules adapt analog process signals e.g. from transducers» Analog output modules convert internal digital values of the PLC to analog process signals e.g. temperature controller
  27. 27. Handout section 1.4.3 Central Processing Unit (CPU) What is a CPU? » The “brain” of a PLC » Controlled by a program called the executive or operating system (OS) » The executive is a collection of supervisory programs permanently stored in memory
  28. 28. CPUFour basic types of CPU operations:» Input and output operation» Arithmetic and logic» Reading or changing contents of memory locations» Jump operations
  29. 29. CPU INTERNAL MEMORY PROGRAM SUBMODULE ACCUMULATOR MEMORY (EPROM/ (RAM) EEPROM/ RAM) TIMERS,COUNTERS, Memory SERIAL INTERFACE PROCESSOR PII PIQ
  30. 30. CPU» The CPU reads in input signal states, processes the control program and controls the outputs.» The CPU provides internal Memory, timers and counters.» Restart procedure can be preset and errors can be diagnosed using the CPU’s LEDs.» The overall Reset on the CPU is used to delete the contents of the RAM.» A PG or a Memory submodule is used to transfer the control program to the CPU.
  31. 31. Handout section 1.4.4 Program Memory Program memory RAM (Random Access Memory) ROM (Read Only Memory) • the memory contents can be • the memory contents can be read and written (modified) read, but cannot be modified • memory contents will be lost when the supply voltage fails
  32. 32. Types of Program Memory Program memory Programmable Non-programmable(Read-write memory) Non-alterable Alterable ROM / PROM UV erasable Electrically erasable EPROM / REPROM EEPROM / EAPROM Semiconductor RAM Semiconductor EEPROM / EAPROM
  33. 33. Memory Submodules» EPROM SUBMODULE An ultraviolet erasing device is used to delete the contents of the submodule» EEPROM SUBMODULE EEPROM submodule can be programmed or erased using a programmer» RAM SUBMODULE Can be used in addition to program storage; and used to test a control program during system startup
  34. 34. Handout section 1.4.5 Power Supply Module » The power supply module supplies the operational voltage for the PLC and provides backup for the RAM with a battery » Backup battery » The backup battery maintains the program and data when the PLC is switch off » The backup battery has a service life of approximately 2 years
  35. 35. Hardware Summary PG External power supplyPS951 Input Output CPU module module Input Output devices devices
  36. 36. Handout section 1.5How Does a Programmable Controller Work? 24 VDC Sensors Program Processor Memory Input modules Power Supply Output modules Actuators / Annunciators GND
  37. 37. Steps of Operation» The sensors are connected to the INPUT MODULES» The processor in the CPU MODULE executes the program and scans the individual input for presence or absence of voltage» Depending on the state of the inputs, the processor directs the OUTPUT MODULES to switch voltages» The ACTUATORS or ANNUNCIATORS are switched “ON” or “OFF” according to the voltage states
  38. 38. Handout section 1.6 Signal States and Sensor Contacts » There are only two different states: SIGNAL STATE “0” = voltage not present = OFF SIGNAL STATE “1” = voltage present = ON » The sensor is a The sensor is Voltage at input Signal state NO contact activated present 1 NO contact not activated not present 0 NC contact activated not present 0 NC contact not activated present 1
  39. 39. Handout section 1.7 Addressing of Inputs and Outputs » The addressing of inputs and outputs are identified by an operand identifiers and the parameter » Operand identifiers: I - Input Q - Output » Parameter: (consists of a byte and a bit address) 0.0 … 0.7 (where 0. is the byte; 0…7 are the bit addresses) 1.0 … 1.7
  40. 40. Types of Addressing Absolute Symbolic » example: » example: » A I 0.0 » A “System_On” » = Q 8.0 » = “System_On” » A I0.4 » A “M_FORW” » = Q20.5 » = “MOTOR_FOR” » Call FC18 » Call “COUNT” Symbol Address Data Type Comment MOTOR_FOR Q20.5 BOOL Motor moves forward COUNT FC18 FC18 Count bottles SYSTEM_ON I0.0 BOOL Switch system ON SYSTEM_ON Q8.0 BOOL Indicator: “System is ON” M_FORW I0.4 BOOL Pushbutton: Motor forward Max. 24 character Max. 80 character
  41. 41. Handout section 1.8.1 Program Representation - LAD LAD - Ladder Diagram I 0.0 I 0.1 Q 4.0 ( ) » The graphical representation of a control task using symbols to DIN 19239 » Very similar to traditional circuit diagrams, but the current paths are arranged horizontally instead of vertically
  42. 42. Handout section 1.8.2 Program Representation - FBD FBD - Function Block Diagram I 0.0 I 0.1 & Q 4.0 » The graphical representation of a control task using symbols to DIN 40700 and DIN 19239 » Inputs are arranged on the left side while outputs on the right
  43. 43. Handout section 1.8.3 Program Representation - STL STL - Statement List A I 0.0 A I 0.1 = Q 4.0 » The control statement describes the task with mnemonic abbreviations of function designation (DIN 19239) » Each method of representation has special characteristics and specific limits » If certain rules are followed, translation into all three methods of representation is possible
  44. 44. Handout section 1.8.4 Operation And Operand Operation; Describes the function to be carried out (what is to be done) e.g Binary operations, Digital operations and Organizational operations Operand; START FROM HERE
  45. 45. Handout section 1.8.4 Operation And Operand LAD FBD STL OPERATION + OPERAND OPERAND + OPERATION OPERATION + OPERAND I 0.0 M 80.0 I 0.0 A I 0.0 M 80.0 & A M 80.0 OPERATION + OPERAND Q 4.0 ( ) = Q 4.0 = Q 4.0
  46. 46. Handout section 1.9 Program Execution PLC Scan Function: » Read the status of all inputs and outputs » Examine the application program instructions » Execute the control program
  47. 47. Handout section 1.9.1 Linear Program Scanning » Statements are scanned linearly » At the end of the program, scanning starts again from the beginning » This is also referred to as cyclical scanning » Linear program scanning is used mainly for simple, small-scale control schemes
  48. 48. OB1 Linear program scanning» OB = Organization Block» Every program must have OB1 OB1 A I 0.0 A I 0.1» When the PLC is set to run, the = Q 4.0 PLC will look for OB1 only in the : : user memory and execute it : BE» Other blocks can be called from OB1 with the “jump” command Cyclic program execution
  49. 49. Handout section 1.9.2 Structured Program Scanning Operating FC1 system A I 0.0 » Complex tasks are subdivided A I 0.1 = Q 4.0 into clearly differentiated sub- OB1 : Cyclic program execution tasks : JU FC 1 : BE JU FC 4 » i.e. the program is divided into : small, easy-to-follow program : FC4 : blocks, organized according to BE A Q 4.0 different functions A I 0.2 = Q 5.0 : : : BE Structured program scanning
  50. 50. Linear programming Structured programmingOB1 FC 1 Network 1 Network 1 A I 0.6 A I 0.6 A I 0.7 A I 0.7 = Q 4.2 OB 1 = Q 4.2 Network 2 A I 0.7 Network 2 Network 1 A I 0.5 A I 0.7 JU FC 1 = Q 4.3 A I 0.5 BE JU FC 4 = Q 4.3 Network 3 BE FC 4 A Q 4.2 Network 1 A I 0.2 A Q 4.2 = Q 5.5 A I 0.2 = Q 5.5 BE BE
  51. 51. Handout section 1.9.3 Program Execution Input Process Program in Process Output 24 VDC module input image the RAM output image module GND 1 0 I 0.0 A I 0.0 0 Q 4.0 A I 0.1 I 0.1 P = Q 4.0 P I I 1 O I 0.5 I O I 0.7 Q Q 4.3 1 I 0.5 = Q 4.3 BE: 1 I 0.7 Input cycle Program execution Output cycle
  52. 52. PII - Process Input Image Update PII» A buffer of input signals» Update just before program execution starts Execute Program» Not updated during program Logic execution» Logic executed based on status in PII Update Output» Prevent signal transition during program cycle to affect the program
  53. 53. PIQ - Process Output Image» Updated by the program logic during program execution OB1 PIQ» The contents of PIQ are transferred to the output module at the end of OB1 Copy PIQ to Output Module
  54. 54. Handout section 1.9.4 BLOCK TYPES » ORGANISATION BLOCKS (OB) – Interface between the operating system and the user program » FUNCTIONS (FC) - Contains a partial functionality of the program » DATA BLOCKS (DB) – Are data areas of the user program in which user data are managed in a structured manner » SYSTEM FUNCTION BLOCKS (SFB), SYSTEM FUNCTIONS (SFC) - SFBs and SFCs are integrated in the S7 CPU and allow you access to some important system functions » FUNCTION BLOCKS (FB) - FBs are blocks with a “memory” which you can program yourself » INSTANCE DATA BLOCKS (DB) - Instance DBs are associated with the block when an FB/SFB is called. They are created automatically during compilation
  55. 55. Block Nesting Depth FC 7 FC 4 A I .... FC 1 ..OB1 JU FC 7 .. JU FC4 .. .. JU FC 1 .. ... BE .. ... BE ... BE .. BE
  56. 56. Handout section 1.9.5The Operand Areas (for Siemens S5-95U PLC) » I (Input) Interface from the process to the programmable controller » Q (Output) Interface from programmable controller to the process » M (Memory/Flag) Memory for intermediate results of binary operations » T (Timer) Memory for implementing timers » C (Counter) Memory for implementing counters
  57. 57. Handout section 1.9.6The Addressing of Siemens S7 Operand Areas Addressing Input (I) 0.0 to 0.7 1.0 to 1.7 2.0 to 2.7 3.0 to 3.7 Output (Q) 4.0 to 4.7 5.0 to 5.7 8.0 to 8.7 9.0 to 9.7 Counters (C) 0 to 63 Timers (T) 0 to 127
  58. 58. Handout section 3.0 Topic 3 Programming Basic Functions
  59. 59. Handout section 3.1 The Stages of Project Planning Description of the Problem Assignment Lists Rough Structure of the Control System Program Structure Detailed Structure of the Control System
  60. 60. The Stages of Project PlanningProblem Description» it consists of process schematic, a short description of the task definition, and a list of the sensors and actuatorsAssignment List» the sensors and actuators are allocated to the parameters of the programmable controller» it contains a short functional description as well as the device identifier
  61. 61. The Stages of Project PlanningRough Structure of the Control System» it contains all sub-functions of the process with relevant sensors, actuators and indicatorsProgram Structure» it determines the order in which the LAD, FBD or STL diagram to be draftedDetailed Structure of the Control System» using the assignment list and the program structure, the flow chart contained in the rough structure is refined
  62. 62. Handout section 3.2 Programming AND Operation LAD I 0.0 I 0.1 Q 4.0 ( ) FBD STL I 0.0 A I 0.0 I 0.1 & Q 4.0 A I 0.1 = Q 4.0
  63. 63. Handout section 3.3 OR Operation LAD I 0.0 Q 4.0 ( ) I 0.1 FBD STL I 0.0 O I 0.0 >= 1 Q 4.0 O I 0. 1 I 0.1 = Q 4.0
  64. 64. Handout section 3.4 AND - before - OR Operation LAD I 0.0 I 0.1 Q 4.0 ( ) I 0.0 I 0.2 I 0.2 I 0.3 I 0.1 I 0.3 FBD STL A I 0.0 I 0.0 A I 0.1 & O I 0.1 >= 1 Q 4.0 A I 0.2 I 0.2 A I 0.3 & = Q 4.0 I 0.3
  65. 65. Handout section 3.5 OR - before - AND Operation LAD I 0.0 I 0.1 Q 4.0 ( ) I 0.0 I 0.2 I 0.2 I 0.3 STL A( I 0.1 I 0.3 FBD O I 0.0 O I 0.2 I 0.0 ) >= 1 A( I 0.1 O I 0.1 & Q 4.0 O I 0.3 I 0.2 >= 1 ) I 0.3 = Q 4.0
  66. 66. Handout section 3.6 Programming of NC Contacts and NO Contacts » Physical connection PLC programming The sensor is Signal state NO contact NO contact activated 1 NO contact NO contact not activated 0 NO contact NC contact activated 0 NO contact NC contact not activated 1 NC contact NO contact activated 0 NC contact NO contact not activated 1 NC contact NC contact activated 1 NC contact NC contact not activated 0
  67. 67. Handout section 3.7 Latching Output S3 K2 S1 K1 S4 S2 K2 K1 SET Priority / Dominant SET RESET Priority / Dominant RESET
  68. 68. Handout section 3.8 RS Memory Function S3 K2 S2 R S4 = S1 K1 K2 S Q ( ) SET Priority / Dominant SET
  69. 69. RS Memory Function S1 K1 S3 S S2 = S4 K2 K1 R Q ( ) RESET Priority / Dominant RESET
  70. 70. Try This ! Will the output Q 4.0 beLAD activated when you I 0.0 I 0.1 Q 4.0 activate: ( ) » I 0.0 and I 0.1 ? I 0.2 I 0.3 Q 4.0 ( ) » I 0.2 and I 0.3 ? I 0.4 I 0.5 Q 4.0 ( ) » I 0.4 and I 0.5 ?
  71. 71. The Answer» I 0.0 and I 0.1 = NO!» I 0.2 and I 0.3 = NO!» I 0.4 and I 0.5 = YES …… but why ?
  72. 72. When I0.0 and I0.1 Are Activated...LAD I 0.0 I 0.1 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “1” I 0.2 I 0.3 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “0” I 0.4 I 0.5 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “0” so, Q 4.0 = “0”
  73. 73. When I0.2 and I0.3 Are Activated...LAD I 0.0 I 0.1 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “0” I 0.2 I 0.3 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “1” I 0.4 I 0.5 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “0” so, Q 4.0 = “0”
  74. 74. When I0.4 and I0.5 Are Activated...LAD I 0.0 I 0.1 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “0” I 0.2 I 0.3 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “0” I 0.4 I 0.5 Q 4.0 » the PLC registers in the PIQ ( ) that Q 4.0 is “1” this time, Q 4.0 = “1”
  75. 75. Priority and PIQ
  76. 76. The Problem of Repetitive Outputs» Therefore, when the same output is used more than once in the program, only the last state of the output will be valid due to the PLC dynamically updating the PIQ (Process Output Image)» MEMORY = Memory for intermediate results of binary operations» Memory can be treated as flags/variables» Memory can be used to solve the problem of repetitive outputs
  77. 77. Using Memory…... I 0.0 I 0.1 M 100.0 ( ) I 0.2 I 0.3 M 100.1 ( ) I 0.4 I 0.5 M 100.2 ( ) M 100.0 Q 4.0 ( ) M 100.1 M 100.2
  78. 78. Result of Logic Operation (RLO) Q 4.0 RLO STAT A Q 4.0 …… …… & A( …… ……I 0.0 Q 5.0 O I 0.1 …… ……I 0.1 >=1 O I 0.2 …… ……I 0.2 O I 0.3 …… …… ) = Q 5.0 …… ……
  79. 79. Parenthesized Function Mathematics Logic OperationMultiplication Before Addition AND before OR4 X 8 + 3 X 2 = 38 RLO STAT A I 0.0 1 1 A I 0.1 1 1 O 1 A I 0.2 0 0 A I 0.3 0 1 = Q 4.0 1 1
  80. 80. Parenthesized Function Mathematics Logic OperationAddition Before Multiplication OR before AND4 X (8 + 3 ) X 2 = 88 RLO STAT A I 0.0 1 1 A( 1 O I 0.1 1 1 O I 0.2 1 0 ) 1 A I 0.3 1 1 = Q 4.1 1 1
  81. 81. Handout section 4.0 Topic 4 Numerical Systems and Data Formats
  82. 82. Handout section 4.1 Comparison of Number Systems
  83. 83. Binary and Hexadecimal
  84. 84. Handout section 4.2 Bit, Byte and Word Addresses
  85. 85. Handout section 4.3 Force Variable and Data Format Force Variable » Display the signal status from memory (PII, PIQ and flag) of the CPU » Used to access the system data area of the CPU and modify the data
  86. 86. Force Variable and Data Format Data Format» KM - bit pattern» KH - hexadecimal» KF - sign number ( - 32768 to +32767 )» KT - time value» KC - counter value» KY - left hand and right hand byte (high / low byte)» KS - alphanumeric character
  87. 87. Handout section 4.4 Load and Transfer Operations Characteristics: » They are used to perform operations on a whole byte or word in memory » They are unconditional operations i.e. They are performed by the processor in each cycle Functions: » Exchange information between various operand areas » Prepare times and counts for further processing » Load constants for program processing
  88. 88. Load Operation L IB 0 ACCUM 2 ACCUM 1 L IB 1Byte d Byte c Byte b Byte a PII IB 0Byte b Byte a 0 IB 0 IB 1 0 IB 0 0 IB 1 Information from PII
  89. 89. Transfer Operation T QB 0 ACCUM 2 ACCUM 1 Byte d Byte c Byte b Byte a PIQ Byte a QB 0 Byte d Byte c Byte b Byte a Information in the PIQ
  90. 90. Handout section 4.5 Arithmetic and Assignment of Accumulator
  91. 91. Handout section 4.6 Binary Coded Decimal (BCD)
  92. 92. Handout section 5.0 Topic 5 Timer Operations
  93. 93. Handout section 5.0 Fault Indication with Timer Function
  94. 94. Handout section 5.1 Inputs and Outputs of a Timer
  95. 95. Handout section 5.2.1 Types of Timer - Pulse Timer (SP)
  96. 96. Handout section 5.2.2 Extended Pulse Timer (SE)
  97. 97. Handout section 5.2.3 On Delay Timer (SD)
  98. 98. Handout section 5.2.4 Stored On Delay Timer (SS)
  99. 99. Handout section 5.2.5 Off Delay Timer (SF)
  100. 100. Handout section 5.3 Specifying the Time Period
  101. 101. Time Value and AccuracyExample: KT 500.1 500 X 0.1S 49.9s …….. 50.0s KT 050.2 50 X 1S 49s ………... 50s KT 005.3 5 X 10S 40s ………... 50s
  102. 102. Load and Transfer Timer Value
  103. 103. Handout section 5.4 Return Operations » BE (Block End) » the return operation is performed unconditionally » it is always the last statement in the block » BEU (Block End Unconditional) » the return operation is performed unconditionally » statements can follow BEU, but they will not be executed » BEU is often used during commissioning so that individual parts of the program can be tested » BEC (Block End Conditional) » the return is made dependent on a condition and is only performed if the condition is satisfied
  104. 104. Block End Operations BEC, BEU and BE FC1 : is always executed OB1 :A I 0.6 :BECSystem : is executed only : :JU FC1 when I 0.6 = “0” :BE :A I 0.0 :JC FC 2 FC2 : : :BEU is executed only : : when I 0.0 = “1” :BE :JU FC3 is not :BE executed FC3 : is not executed : :BE
  105. 105. Handout section 6.0 Topic 6 Counter Operations
  106. 106. Handout section 6.0 Counter
  107. 107. Counter OperationsCU - count upCD - count downS - set counter to the count value (CV)CV - the count valueR - reset the counter (count value = 0)BI - counter output as binary numberDE - counter output as BCD numberQ - counter status Q = 0 when count value = 0 Q = 1 when count value > 1
  108. 108. Handout section 6.1 Load and Transfer for Counter
  109. 109. Handout section 6.2 Timing Diagram
  110. 110. Assign an Initial Value to a Counter (S)Assign Value (CV)» constant KC 0 to 999» input word IW ….....» output word QW …...» flag word FW …....» data word DW …...
  111. 111. Counter Input
  112. 112. Handout section 6.3 Counter Output
  113. 113. Handout section 6.4 Comparator Types of comparison: !=F compare for equal to ><F compare for not equal to >F compare for greater than >=F compare for greater than or equal to <F compare for less than <=F compare for less than or equal to
  114. 114. Comparison Operations» The comparison operations compare two digital values in accumulator 1 and accumulator 2» The result of comparison produces an RLO:» Comparison satisfied RLO = “1”» Comparison not satisfied RLO = “0”
  115. 115. Handout section 6.4 Comparator
  116. 116. THE END

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